This invention relates to an abnormal state diagnosis method for an oil temperature sensor of an automatic transmission which is configured to diagnose an abnormal state of an oil temperature sensor value by a mutual diagnosis between an engine control module and an automatic transmission control unit.
A patent document 1 (Japanese Patent Application Publication No. 7-301315) discloses an abnormal state diagnosis method for an oil temperature sensor of an automatic transmission which is configured to determine an abnormal state judgment of the oil temperature sensor based on a judgment that an abnormal value continues during a predetermined time period or more when an oil temperature sensor value indicates the abnormal value.
Moreover, a patent document 2 (Japanese Patent Application Publication No. 2004-11869) discloses an abnormal state diagnosis method for an oil temperature sensor of an automatic transmission in which an AT control unit receives signals from an engine intake air temperature sensor and an outside air temperature sensor, and which is configured to compare the outside air temperature and the oil temperature, and to judge that the oil temperature sensor is in the abnormal state when the oil temperature is lower than the outside air temperature.